In a conventional surface polishing machine for a glass plate, as is typified by those manufactured in the Speedfirm Company, the glass plate is polished in a state in which abrasive material is supplied onto a rotating polishing base plate on which the glass plate is pressed by means of a holding pad unit which holds and rotates the glass plate.
In a further conventional surface polishing machine for polishing the surface of the glass plate, a holding pad member which holds a glass plate is also moved in an arc in addition to the above described means to flatly polish the surface of the plate glass.
In each of these conventional surface polishing machines, however, the polishing base plate is required to keep with extremely high flatness a plane in which the base plate is rotated. Due to this requirement, the polishing base plate is substantially limited in size, so that the glass plate to be polished is limited in the size thereof. In addition, since the polishing base plate is rotated, the abrasive material having supplied is immediately flowed radially outward by centrifugal force, so that it is difficult to constantly keep the abrasive material between the glass plate and the polishing base plate. In addition, since the rotating polishing base plate has an outer peripheral portion differ from inner peripheral portion in peripheral speed, it is hard to uniformly polish the surface of the glass plate. Further, in any of the conventional machines, it is necessary to stop rotation of the base plate each time the surface polishing operation of the glass plate is finished and the thus finished glass plate is replaced with a new one to be polished. Therefore, any of the conventional surface polishing machines is extremely poor in work rate.
In view of the above disadvantages, an object of the present invention is to provide a surface polishing machine for polishing a surface of glass plate with high flatness without any limitation of the size of glass plate to be polished.
It is another object of the present invention to provide a machine for polishing a surface of glass plate in a state in which abrasive material is kept in a suitable condition between the glass plate and a polishing base plate so as to further facilitate surface polishing operation.
It is further another object of the present invention to provide a surface polishing machine for polishing a surface of glass plate with extremely high uniformity.
It is still further object of the present invention to provide a machine for polishing a surface of glass plate with remarkably improved work rate in a surface polishing operation.